The invention relates to substrate processing systems, and more particularly, to systems for accessing and orienting substrates such as semiconductor wafers during integrated circuit fabrication.
Substrates such as semiconductor wafers are processed in micro environment enclosures in which conditions are carefully managed such that temperature and humidity are controlled, and use is made of air filtration systems which remove contaminants that would otherwise corrupt the delicate manufacturing procedures involved. Complex systems are used to effect these controls, and expedients used include establishing laminar flows within the micro environment enclosure to direct air flow towards the filtration devices.
The substrates, prior to loading into the micro environment enclosure, are conventionally handled in protective containers which seal out contaminants. One type of industry standard container is referred to as a front opening universal pod (FOUP) and is used to store the substrates in a stacked arrangement. The door of the FOUP, from which the interior is accessed, is disposed at the front and is detachable such that when the FOUP is engaged with the enclosure of the micro environment in which the substrates are to be processed, the door is removed to a remote location and access to the substrates is facilitated. The micro environment system has one or more processing stations into and out of which the substrates, for instance semiconductor wafers, are transferred from the FOUPs.
When the wafers are ready for processing, the pod containing the wafers is docked with an interface portion of the micro environment, which may be referred to as a load lock chamber. The load lock chamber is provided with a port having a door supported therein. The door, normally closed to preserve the micro environment conditions, is opened when the pod is in the docked position. A door of the pod is also opened, thereby permitting transport of the semiconductor wafers between the pod and the micro environment through the load lock chamber. The mating of the pod to the load lock chamber is carefully controlled, and the door opening process coordinated, so that the integrity of the micro environment is undisturbed during the loading and unloading process.
Opening and closing of the pod and load lock chamber doors is automated. An opening mechanism provided in the load lock chamber simultaneously engages both doors, often sealing them together to sandwich contaminants therebetween, and removes them along a transport path to a remote position to thereby facilitate transfer of the wafers, by a different loading and unloading mechanism, between the pod and the load lock chamber. Prior art devices of this type include U.S. Pat. No. 5,607,276 to Muka, et al., U.S. Pat. No. 5,609,459 to Muka, U.S. Pat. No. 5,613,821 to Muka, et al., and U.S. Pat. No. 5,664,925 to Muka, et al. A typical prior art opening and closing configuration relies on an upright lever which engages both the pod and load lock chamber doors. The lever then swings internally, away from the pod, along a shallow angle, pulling the doors internally with it. When sufficient clearance is thus achieved, the lever, along with the doors, descends downward within the load lock chamber, leaving the pod-load lock chamber interface clear for access to the interior of the pod. The substrates are then withdrawn from the pod, processed, and returned, using suitable robot arms. Once processing is complete and the substrates returned to the pod, the process is reversed and the pod and load lock chamber are again sealed from each other.
Another prior art device, the subject of U.S. Pat. No. 6,142,722, is directed to opening and closing pod and load lock chamber doors using the wafer handling robot itself. The arm of the robot, using a specialized, detachable tool, engages both doors and transports these to a dedicated location within the micro environment. The arm then accesses the substrates in the pod, delivers them to the appropriate processing stations, then returns them to the pod and reseals the pods with the retrieved doors.
FIG. 1 shows a prior art semiconductor processing system in which a robot 10 is enclosed within a micro-environment enclosure 12. Various processing stations 14, which may include storage pods for holding a plurality of stacked substrates (not shown), are in communication with the micro environment within the enclosure 12. Robot 10 is provided with a robot arm 16 which supports an end effector 18 used to hold semiconductor substrates as these are retrieved from the various stations 14. Disposed within micro environment enclosure 12 is an alignment device 15 to which the semiconductor substrates are transported by robot arm 16 in order to determine and/or adjust the orientation of the semiconductor substrates. To that end, substrates such as wafers are provided with a notch at the edge, which notch is suitably detected by, for example, a photoelectric sensor provided in alignment device 20. During operation, robot 10, for example, retrieves a wafer from one of the stations 14, transports the wafer to alignment device 15 where its orientation is determined and/or adjusted, then deposits the wafer at a different station (or the same station) 14.
The aforementioned prior art alignment system introduces several additional steps associated with the alignment device 15. For example, the substrate has to first be transported to the alignment device 15 and deposited therein, then after orientation determination and/or adjustment, the substrate has to be retrieved from the alignment device and then transported to the destination station 14. This represents a disruption in the flow path and introduces various steps which increase processing time and potential malfunction.
The invention overcomes shortcomings of the prior art, providing an integrated substrate handler for use in a system in which the interior of a substrate storage pod having a removable pod door is accessed from the interior of a micro environment enclosure. The integrated substrate handler is provided with an enclosure door mounted for movement between one or more open positions and a closed position, wherein in an open position the interior of the substrate storage pod is accessible from the interior of the micro environment enclosure. The integrated substrate handler is also provided with a pre-aligner mounted for movement with the enclosure door, the pre-aligner being adapted to detect the orientation of a substrate.
Further in accordance with the invention, a method is provided wherein an enclosure door and a pre-aligner are moved incrementally to a plurality of open positions. A substrate is transported from the interior of the substrate storage pod to the pre-aligner, and the orientation of the of the transported substrate at the pre-aligner.
Further in accordance with the invention, a method is provided wherein the an enclosure door and a pre-aligner are moved to a plurality of open positions corresponding to storage locations of a substrate storage pod, and a substrate is transported between the interior of the substrate storage pod and the interior of a micro environment enclosure.